02_sleeper_pads_for_ballasted_tracks.pdf

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Sleeper Pads

for Ballasted Track


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S

leeper pads offer one opportunityto meet these challenges: They

preserve the superstructure, improvethe quality of the track geometry andreduce disruptive vibrations, both inthe track and in the switch.

Sleeper pads offer the following

advantages:

Reduction of maintenance expenses Lengthening of the service life of the

track structure Reduction of disruptive vibrations

Sleeper pads offer operators theopportunity to significantly reduce theannual maintenance costs for tracksand switches.

Elastic sleeper pads from Getznerare a further development of theclassic railway superstructure. Theproducts are placed directly beneaththe track sleepers and increase thevertical elasticity in the superstructure.With sleeper pads, the load of the railcars is evenly distributed over theelastic components in the subsoil.Sleeper pads with defined elasticproperties significantly reduce wearon the rail line.

Highly elastic sleeper pads can alsorepresent an economical alternative tosub-ballast mats as a vibration-isolat-ing measure.

Getzner has produced sleeper padssince 1990. Today, they are used

successfully around the world on alltypes of railway lines, from high-speednetworks to regional transport.

Increasing operational loads and

speeds in modern railway traffic

present new technical and economic

challenges to railway managers

around the world.

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The elastic solution forballasted tracks andswitches


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FunctioningPrinciple

2

4

Load distribution

with sleeper pads

Load distribution

without sleeper pads


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The most common type of super-structure used in the world isballasted track. Ballast, as the weak-est link in the system, is subject tolatent dynamic shifting. Constant loads(ballast compression) lead to wearand breaking up of the rocks. Theseeffects diminish the quality of the trackgeometry, and the track bed must betamped.

5

Distribution of the axleload over a largernumber of sleepers

The elastic properties of the

sleeper pads lengthen thebending line of the rails. The loadfrom the train is distributed overa larger number of sleepers andtherefore over a larger area. Thisreduced average compressionalso reduces the load on theballast.

Weakening of the dynam-ic forces and vibrationsin the ballast

Sleeper pads from Getzner

reduce the direct dynamic loadon the ballast. They reduceshifting of the ballast as well assettling of the track.

The effective installation of sleeper

pads slows down this process in the

following ways:

Padded sleepers

Increase of the contactsurface between sleeperand ballast

The unique properties of the

polyurethane material fromGetzner result in an ideal embed-ding of the ballast in the surfaceof the sleeper pads, stabilizingthe top-most ballast layer. Thisyields an increase in the contactsurface between sleeper andballast from about 8% (withoutpadding) to up to 35% (withpadding).


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The effective use of sleeper pads from

Getzner results in a reduced load on

the ballast. This in turn reduces

ballast break-up and abrasion.

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Applications3

Improvement in the

long-term behavior ofballasted track

The ballast is optimally embeddedthanks to the plastic properties ofthe pad, resulting in decreased ballastshifting. This method directly helpspreserve the ballast bed and slowssettling of the track considerably.Experiences in recent years have

shown that the length of tampingintervals can be at least doubled withthis procedure. The positive effect ofsleeper padding becomes clear particu-larly quickly in areas subject to heavyloads, such as switches, structures ortrack sections with very small curveradii.

The advantages of padded sleepers areparticularly impressive on heavy-ladensections with up to 37 tons of axle load.

Intervention threshold

Sufficient

Good

Very good

2001 20032002 2004 2005

Year

2006 2007 2008

Insufficient

Straight track section 1 (unpadded)

Straight track section 2 (unpadded)

Track section radius 425 m with padded sleeper

Stop in station area (unpadded)

Track geometry quality

Changes in track geometry

quality on a test stretch in

Austria since 2001.

The improvements in track

quality in track sections 1

and 2 as well as the station

area were achieved through

tamping.


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D

epending on the maximum per-missible rail deflection, padded

sleepers achieve insertion losses onthe order of 10 dB(v) to 15 dB(v) (at63 Hz).

Vibration protection and

reduction of secondaryair-borne sound

Highly elastic pads offer a simple

method for reducing vibrations on

railway lines that is cost-effective in

comparison with sub-ballast mats. In

addition, they exhibit all the positive

properties of elastoplastic padding.

No significant changes to the directlyemitted air-borne noise have yet beenidentified.

Secondary air-borne noise arises dueto the sound emission of a structurethat is stimulated to vibrate, forinstance by a passing train.

This applies in particular to metalstructures, such as steel bridges andviaducts. Elastic sleeper pads with

7

Effect of sleeper padding

20

10

0

5 86,8 10 12,5

Frequency (Hz)

16 20 25

30

31,5 40 50 63 80 100 125 160 200 250-10

Insertion

loss(dB)

Reduction

Amplification

Open track section

Tunnel far track bench

Tunnel near track bench

The vibrations are reduced in the

critical frequency range, which also

reduces the emissions to the

neighboring environment.

Source: Kstli K.; Sleeper Padding for Reduction of Structure-Borne Noise Immissions; p. 10; conference articles, 10thSymposium on Structural Dynamics and Vibration Measurements,Ziegler Consultants 2007.

vibration-isolating characteristics are avery effective measure for reducingsecondary air-borne noise.


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Short waves are periodic bumps in the

track surface.

The different bedding stiffnessvalues result in a dynamic loadwhen a train passes. This leads to arapid wearing of the track, whichincreases maintenance costs and

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Reduction ofshort wave formation

Specically dened elas-ticity for padded switches

The bedding stiffness varies over the

course of a switch. This is due to the

different sleeper lengths and stiffen-

ing components, such as the frog,

check rails or wing rails.

reduces passenger comfort. In addition,vibrations are transmitted to nearbybuildings via the subsoil.

Getzner offers a combination ofdifferent sleeper pads (stiffnesses)specifically for switches. The loadtransmission to the superstructure canbe homogenized with these pads.Differences in deflection are minimized,resulting in smoothing of the switch.

Multi-year studies have shown thatsleeper pads significantly slow theoccurrence of such track damage. Thisis particularly noticeable on narrowtrack bends that are susceptible toshort waves.

0.15

0.10

0.05

2003 2004

Time

2005

0.20

2006 2007 20080.00

Averagewavedepthinmm

(Track bend radius: 230 m)

0 million t*

5 million t*

10 million t*15 million t*

20 million t*

25 million t*

Withoutsleeper pad

With Sylomer

sleeper pad withbedding modulus~0.15 N/mm3~

*Track loadin gross tons

Short wave development in track bends over time

Final report Hieflau,

University of Innsbruck 2001


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An even load pattern is also produced,which helps preserve the ballast.

Sleeper pads from Getzner alsocontribute here to lengthening theintervals between tamping andmaintenance work. Increased passen-ger comfort and lower life-cycle costsmake sleeper pads from Getzner apopular solution among railwaymanagers.

BridgeBallasted track

Smoothing of deflection during trainpasses

Increased passenger comfort Preservation of the ballast Reduction of disruptive vibrations Reduction of life-cycle costs (LCC)

The deflection during train passes canbe simulated with a specially developedcomputer model and optimized throughthe effective use of Getzner pads.

Adaptation of trackstiffness at transitions

Sleeper padding helps to decreaselarge jumps in stiffness andthereby deflection as well as to reducevoids under the sleepers. These occurprimarily at transitions where super-structures with different stiffnessvalues meet. The sleeper paddingresults in a more homogenous trainpassage as well as preservation of thesuperstructure components.


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One observation is a lengthening ofintervals between tamping work bya factor of 2 to 2.5 thanks to the use ofsleeper pads. If one considers thetamping cycle as an indicator for theachievable service life of a track,longer periods between tamping work

Using Sleeper PadsPays Off

4

The extent to which the use of sleeper

pads alters the track geometry quality

has been systematically recorded for

several years. The results are continu-

ously influencing development work.

Consideration of the life-cycle costs (LCC)when using sleeper pads

0

60%

40%

20%

Superstructure

with 60E1 rails and

padded sleepers

Conventional super-

structure with 60E1 rails

and concrete sleepers

100

80%

100%

120%

0%

61

16

23

71

48

1013

Annual costs

Depreciation

Operating complication costs

Maintenance costs

Statistical analysis

(interest rate 0%)

point to a significant lengthening of thelife of the entire track bed.

In addition, if costs for operatingcomplications that arise from trackclosures for maintenance work areconsidered, sleeper pads are anextremely economical investment,particularly on track sections subjectto heavy loads.

Composition of the normalized annual costs

(heavily used track)


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Sleeper pads are used for vibrationprotection, to provide elasticity forlarge bridge structures, to improvetrack geometry quality and to reducetrack maintenance costs.

The sleeper pads from Getzner haveoutstanding long-term properties. Thisis demonstrated by sleepers with

Widely proven

Almost all major railway companies in

Europe have successfully used sleeper

pads from Getzner for over 18 years.

Getzner padding SLB 2210G after 190

million total tons. The plastic impres-

sions in the material prevent shiftingby the top ballast layer. No cracks or

perforations can be seen in the

padding.

Getzner pads that have been removedfor testing. In addition, measurementstaken on padded track sections alsoverify the excellent quality of thesleeper pads.

To ensure a long service life for sleepers,the durability of all types is inspectedaccording to BN 918 145-1. These testsare either performed externally at acertified testing agency (e.g. MunichUniversity of Technology) or internallyon Getzners large test bench.

Experience withSleeper Soles

5

11

Getzners large test bench


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Sleeper Selection The RightGetzner Pads for Every Application

6

Getzner sleeper pads, thebroad product selection

Three materials available withdifferent stiffness values com-pletely cover the application spectrumfrom highly effective vibration protec-tion to improvement of track geometryquality.

The three materials:SLB Elastoplastic materialSLS Elastic material with damping

propertiesSLN Highly elastic material without

damping

Freight train

(heavy axle loads)

37 0 kN

Standard-gauge railway

250 kN

Underground line

1 20 kN

Tram line

100 kN

SLNtypes

SLStypes

SLBtypes

Axle load

Vibration protection


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Getzners specialty is microcellular

polyurethane elastomers with a wide

range of properties for railway

superstructures. Sylomerand

Sylodyncomponents have proven

themselves for decades under ex-

treme conditions in a wide range of

industries.

If a reduction of vibrations is theprimary aim, SLS-type (Sylomer)elastic pads and the highly effectiveSLN (Sylodyn) types are used.

While pads made of Sylomerstillexhibit certain damping properties,solutions with Sylodynachieve anearly identical relationship betweenstatic and dynamic stiffness. Thismakes an extremely effective solutionpossible even with minimal additionalrail deflection.

The right pad forevery track

Getzner offers the optimal sleeperpad for every application: from theelastoplastic SLB types exclusively forimprovement of track geometry qualityto the highly elastic pads made ofSylomer(SLS types) and Sylodyn(SLN types) for effective reduction ofvibrations.

SLB-type elastoplastic pads are used toreduce the load on the ballast. Theoptimized material properties of these

types permit a particularly stableembedding of the ballast. The highdamping of these pad types has apositive effect on the vibration behav-ior of the sleeper.

Elastoplastic pads reduce the annualmaintenance costs and lengthen theservice life of a track.

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Getzner has the optimal pad type for

every application. The appropriate

types are selected according to the

maximum permissible rail deflection

under a defined load.

Selection of theideal Getzner pad

The individual pad types within amaterial group differ primarily interms of their elasticity. The elasticityis determined using the beddingmodulus. This takes place according toDIN 45673-1 in a test on a ballastprofile slab (standard ballast slab).Getzner provides optimized pad typesfor tram lines, underground lines, rapidtransit, standard-gauge railways,high-speed tracks and special applica-tions, such as heavy axle loads of up to37 tons.

Oresund Bridge


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SecureFastening

7

Assembly at thesleeper plant

Sleeper pads from Getzner can be

adapted to every sleeper type.

Pads for concrete sleepers aretypically manufactured with aninstallation grate (G at the end of thetype designation). This unique installa-tion grate from Getzner is integratedinto the padding and permits a full-surface attachment of the pad to thesleeper. The installation grate ispressed into the concrete while it is stillmoist during the production of thesleepers. The form-fitting, full-surfaceconnection ensures a lasting bondbetween the pad and the concretesleeper independent of the productionprocess and concrete consistency.

The connection process requires noadditives or extensive preliminary work

while fulfilling even the very highrequirements of the standard BN 918145-1. If desired by the customer, padscan also be attached to concretesleepers that have already hardened.In such cases, the sleeper pads aredelivered without an integratedinstallation grate. The pads are gluedon with a suitable adhesive, whichGetzner can also supply, if desired.

Padded sleepers can be installed

using all typical methods.

Due to the relatively low weight ofthe pads, the number of sleepersper car can remain unchanged. Thereare also no restrictions on trackmaintenance work.

At the transitions between padded andunpadded tracks, it may be necessaryto change the stiffness in stages. Thisapplies primarily to soft pads (beddingmodulus < 0.15 N/mm3). Getznerrecommends using padding with ahigher stiffness over a length of 20 to30 meters for such stiffness adapta-tion.

Installation of paddedconcrete sleepers

Sleeper production

Installation train with switch padding


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InternationalReferences

8

Getzner solutions can be found around

the world as can the Getzner team.

Getzner Werkstoffe is present in themost strategically important partsof the world with its four branch ofces.The company serves practically all ofthe relevant markets in the worldthrough numerous sales partners.

Sleeper Padding for Ballasted Trackreference list (excerpt):

Goal: Sleeper pads for vibration

isolation

Metro Amsterdam East Line,Netherlands

Bruchsal Tunnel, Germany Umega Oka Line, Japan Britomart Station, New Zealand Matstetten-Rothrist, Switzerland Timelkam, Feldkirch and Hallwang,

Austria

Goal: Ballast preservation and im-

provement of track geometry

quality

BB, Austria DB, Germany SBB, Switzerland SNCF, France

Bane Denmark, Denmark KR, Korea Jernbaneverket, Norway CR, Czech Republic Infrabel, Belgium ADIF, Spain

Getzner projectsspeak for themselves

Goal: Elastically supported

switches

BB, Austria DB, Germany SBB, Switzerland CR, Czech Republic Pro Rail, Netherlands Jernbaneverket, Norway


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Getzner Werkstoffe GmbH

Herrenau 56706 BrsAustriaPhone +43-5552-201-0Fax [email protected]


Am Borsigturm 1113507 BerlinGermanyPhone +49-30-405034-00Fax [email protected]


Nrdliche Mnchner Str. 27a82031 GrnwaldGermanyPhone +49-89-693500-0Fax [email protected]


Middle East Regional OfceAbdul - Hameed Sharaf Str. 114Rimawi Center - ShmeisaniP. O. Box 961 303Amman 11196, JordanPhone +9626-560-7341Fax [email protected]

Nihon Getzner K.K.

Landmark Plaza, 8FShiba Koen 1-6-7, Minato-ku105-0011 Tokyo, JapanPhone +81-3-5402-5340Fax +81-3-5402-6039

www.getzner.com

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opyrightbyGetznerWerkstoffeGmbH|03-2009

02_sleeper_pads_for_ballasted_tracks.pdf

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